Process for producing soy milk

ABSTRACT

A process for producing a soy milk which involves adding a solidifying agent to a soy milk employed as the starting material, homogenizing the mixture, directly heating instantaneously with steam and then homogenizing again. The thus obtained soy milk has a body taste and is in the form of a liquid with a low viscosity. When heated, it is never solidified again. Therefore, this soy milk is appropriately usable in additives for pastry or bread doughs, fillings such as creams, materials for fermented food products, materials for drinks, materials for ice creams, materials for desserts, materials for fish paste products, materials for prepared foods, etc.

TECHNICAL FIELD

The present invention relates to a method of producing a soymilk with animproved flavor.

BACKGROUND ART

Recently, intention to improve and preserve health with the aid of foodshas increased and significance of vegetable foods has been increasinglyrecognized, resulting in expectation of a soymilk to serve as such avegetable food. In response to the expectation, improved techniques forproducing a soymilk have been developed independently of methods ofproducing a tofu (bean curd). As a result, soymilks in which bean smell,raw smell, bitter taste and astringent taste have been suppressed so asto be easy to drink have become commercially available. The wide varietyof the improved techniques include removal of seed coats and hypocotyls,heating for inactivation of enzymes, treatment upon crushing andgrinding, treatment upon separating tofu refuse, steps of sterilizationand deodorization.

Such improved soymilks are remarkably easy to drink as compared toconventional soymilks. However, they still remain to be improved if theyare used as materials for drinks or desserts although the bean smell,raw smell, bitter taste and astringent taste characteristic of soybeanshave been improved to some extent.

In order to overcome the problems concerning the flavor of soymilks,they were conventionally seasoned with sweeteners, various flavors,fruit juices etc. for masking bean smell, raw smell, bitter taste andastringent taste characteristic of soybeans. However, such treatmentsare still insufficient. In addition, the flavors are unnatural. Nomethod has been developed for producing a soymilk which can be utilizedas a kneading material for confectionery or bakery and a fillingmaterial such as cream, as well as materials for fermentation foods,drinks, ice creams, desserts, aquatic or live-stock paste products,cooked daily dish and the like while retaining the natural flavor ofsoybeans

The present inventors directed their attention to the excellent flavorof a tofu prepared from a soymilk by a traditional method. Then, thepresent inventors began to examine a method of producing a liquid tofuwith a tofu flavor, i.e., a soymilk which has low viscosity, does notre-coagulate, and can be utilized as a kneading material forconfectionery or bakery and a filling material such as cream, as well asmaterials for fermentation foods, drinks, ice creams, desserts, aquaticor live-stock paste products, cooked daily dish and the like. In thecourse of the examination, it revealed that various methods forenriching soymilks with calcium have been examined, which providesimilar effects, although the methods were developed for differentpurposes than those of the present inventors. Specifically, variousmethods have been proposed as follows for overcoming problems ofincreased viscosity due to aggregation of calcium with proteins in asoymilk or of coagulation into tofu-like state upon addition of thecalcium into the soymilk.

For example, JP-A 52-90662 and JP-A 53-96356 disclose a methodcomprising adjusting pH by adding calcium hydroxide, a fat and anemulsifying agent to a soymilk. JP-A 53-183669 discloses a methodcomprising adding a chelating agent. JP-A 54-95771 discloses a methodcomprising adding casein and/or dephosphorylated β-casein to an aqueoussolution of soybean protein followed by addition of a calcium saltsolution. JP-A 59-6839 discloses a method comprising partiallyhydrolyzing separated proteins, adding a fat and calciumglycerophosphate, and homogenizing the mixture. JP-A 59-173044 disclosesa method comprising adding calcium lactate and sodium hydrogencarbonatein combination to a soymilk. JP-A 60-47636 discloses a method comprisingincorporating a calcium compound into a soymilk in the presence ofglycerol or propylene glycol. JP-A 61-25458 discloses a methodcomprising adding saccharide lime to a soymilk or a soybean proteindrink and neutralizing the mixture with an organic acid. JP-A 61-249355discloses a method comprising contacting a soymilk with a calcium-typestrong acid cation-exchange membrane. JP-A 5-308900 discloses a methodcomprising adding calcium to a solution of separated soybean proteinsand various soymilks, coagulating proteins, homogenizing the mixture,adding an acidulant, and homogenizing and heat-sterilizing the mixture.

However, none of the above-mentioned methods teaches a method comprisingadding a coagulant for soybean proteins, then sterilizing the mixturewith direct high-temperature flash heating using steam and homogenizingit.

OBJECTS OF INVENTION

As described above, conventional methods in which a coagulant is addedto a soymilk had problems, including unavoidableness of influence on theflavor of the soymilk due to the coagulant itself, agents used incombination, or change in pH, as well as complexity of operation.

SUMMARY OF INVENTION

The present inventors directed their attention to the excellent flavorof a tofu produced from a soymilk by a traditional method. Then, it wasfound that a liquid tofu having a tofu flavor, in other words, a soymilkwhich has low viscosity, does not re-coagulate, and can be utilized as akneading material for confectionery or bakery and a filling materialsuch as cream, as well as materials for fermentation foods, drinks, icecreams, desserts, aquatic or live-stock paste products, cooked dailydish and the like has an excellent flavor. Furthermore, it was foundthat a soymilk could be converted into a fine colloidal solution byhomogenizing a tofu-like coagulation formed by heating a soymilk andadding a coagulant thereto. This procedure reduces raw smell, bittertaste and astringent taste inherently associated with a soymilk andmakes the soymilk have a flavor as good as a tofu. In addition, it wasfound that a soymilk, which has a better flavor, has remarkably lowviscosity and does not re-coagulate upon subsequent heating, can beobtained by treating the fine colloidal solution derived from thesoymilk with direct high-temperature flash heating using steam and thenhomogenizing it. The present inventors completed the present inventionbased on such new findings.

The present invention provides a method of producing a soymilk,comprising adding a coagulant to a raw soymilk, homogenizing, treatingwith direct high-temperature flash heating using steam, and thenhomogenizing the mixture. The pH of the raw soymilk is preferablyadjusted to 7-8. One or more selected from the group consisting of abittern, a magnesium salt, a calcium salt and glucono-δ-lactone can beused as the coagulant. Preferably, the amount of the added coagulant is2-8% (in the case of magnesium salt or calcium salt, 0.24-1.9% asmagnesium or calcium) based on the crude protein content of the soymilk.The direct high-temperature flash heating is preferably conducted at120-150° C. for 2-10 seconds. The homogenization is conducted using ahomogenizer preferably at a pressure of, without limitation, 5-200kg/cm². The appropriate pH of the produced soymilk is 5.5-7.4,preferably 6.5-7.4.

DETAILED DESCRIPTION OF THE INVENTION

A soymilk made from soybeans is suitably used in the present invention.Soybeans from which seed coats and hypocotyls are removed and which areheated for inactivating enzymes are preferred. A raw soymilk can beobtained by known methods. The pH of the obtained raw soymilk ispreferably adjusted to 7-8 in order to deal with the lowering of the pHcaused by addition of a coagulant. Use of a raw soymilk at pH within therange as described above results in a soymilk at pH 5.5-7.4.

A coagulant used in the present invention includes one selected from thegroup consisting of a magnesium salt such as a natural (salt pan)bittern, magnesium chloride or magnesium sulfate, a calcium salt such ascalcium sulfate, calcium chloride, calcium lactate or whey calcium, aswell as glucono-δ-lactone or a mixture thereof. Either of theabove-mentioned coagulants can be effectively used to reduce raw smell,bitter taste and astringent taste of a soymilk. The bittern and themagnesium salt are more effective in providing a soymilk with good bodysuch as milk taste than the calcium salt. The effect of improving theflavor achieved by using glucono-δ-lactone alone is less than thatachieved by using the magnesium salt or the calcium salt. Therefore, itis preferred to use glucono-δ-lactone in combination with the magnesiumsalt or the calcium salt. In addition, an organic acid such as fumaricacid can be used in place of glucono-δ-lactone.

The amount of the coagulant added in the present invention variesdepending on the coagulant used. The suitable amount is usually, as asalt, 1-4% based on the solid content of the soymilk, or 2-8% (in thecase of a magnesium salt or a calcium salt, 0.24-1.9% as magnesium orcalcium) based on the crude protein content of the soymilk. If theamount of the coagulant is less than 2% based on the crude proteincontent of the soymilk, effect of reducing raw smell, bitter taste andastringent taste of a soymilk cannot be observed. On the other hand, ifthe amount is over 8%, the taste of the coagulant is recognized as atang, the pH lowers, and the flavor is impaired. Furthermore, such ahigh amount makes the subsequent homogenization difficult to conductbecause of the excessive coagulation of the soymilk. In view ofimprovement of the flavor, the amount of the coagulant is preferably3-7% (in the case of magnesium salt or calcium salt, 0.36-1.6% asmagnesium or calcium) based on the crude protein content of the soymilk.

There is no limitation regarding the time at which the coagulant isadded as long as it is added prior to direct high-temperature flashheating using steam. For example, in a case where pre-heating isconducted prior to the homogenization as described below, the coagulantmay be added before or after the pre-heating. If the coagulant is addedin an amount which makes the soymilk coagulate like a tofu, it ispossible to facilitate the homogenization by continuously stirring thesoymilk from the time of addition to the time of homogenization suchthat the soymilk does not separate into aggregates and a supernatant.

Homogenization is not necessarily required if the soymilk to which acoagulant is added is composed of coagulations which can be processedsubsequently in the device for direct high-temperature flash heatingusing steam. However, a soymilk with a coagulant added is usuallyhomogenized because the treatment with high-temperature flash heatingenhances the effect of improving the flavor of the soymilk. Homogenizingmeans such as a known homogenizer can be utilized for thehomogenization. The homogenization can make the subsequent directhigh-temperature flash heating using steam effective. The homogenizationprior to the high-temperature flash heating is conducted using ahigh-pressure homogenizer and the like suitably at a pressure of, forexample, 5-200 kg/cm².

Pre-heating may be conducted prior to the homogenization in order toincrease the reactivity of the coagulant. When a tofu is produced, asoymilk is usually heated to 70° C. or above before and/or after addinga coagulant in order to increase the reactivity of the coagulant. Incontrast, it is not necessarily required that a soymilk is coagulated atthe time of homogenization in the present invention. Thus, the soymilkwith the coagulant added does not need to be heated. Rather, a soymilkwith a more excellent flavor can be obtained by promoting the reactionof the soymilk with the coagulant in the subsequent directhigh-temperature flash heating.

The homogenized soymilk is treated with direct high-temperature flashheating using steam. As used herein, a treatment with directhigh-temperature flash heating refers to a treatment in which steam isdirectly blown into a soymilk to elevate the temperature of the soymilkin a moment. This treatment denatures proteins and the like in thesoymilk and improves the flavor of the soymilk remarkably.

There is no limitation regarding the temperature of the soymilk beforethe high-temperature flash heating. By pre-heating, increase in watercontent due to the blow of steam can be reduced, thereby preventing thesolid content of the resulting soymilk from reducing. A pre-heatingtemperature of, without limitation, 60° C. or above is sufficientlyused. A temperature of 70° C. or above, at which the reaction of thesoymilk with the coagulant is promoted, is not necessarily required.

The high-temperature flash heating of the present invention is directhigh-temperature flash heating using steam. It is considered that suchheating contributes to the prevention of re-aggregation upon re-heatingand the improvement of the flavor as a result of the following. At theinjection portion for steam, an aggregated soymilk is mixed with steam,resulting in further denaturation of aggregated proteins due to the hightemperature and the high pressure. Then, the soymilk becomes lessviscous and the aggregated proteins are converted into fine particles.Furthermore, the reduced pressure in a flash pan provides a deodorizingeffect.

The direct high-temperature flash heating may be usually conducted at120-150° C. or below for one second to one minute, preferably for 2-10seconds.

The direct high-temperature flash heating using steam remarkably reducesthe viscosity of the soymilk aggregated by adding the coagulant. Theviscosity can be further reduced by the subsequent homogenization.

The homogenization following the high-temperature flash heating can alsobe conducted utilizing known homogenizing means such as a high-pressurehomogenizer and the like as in the case of the above-mentionedhomogenization preferably at a pressure of, without limitation, 5-200kg/cm².

The soymilk of the present invention produced by the method as describedabove has reduced raw smell, bitter taste and astringent tasteassociated with a raw soymilk, has good body such as milk taste as wellas a good flavor, has low viscosity, and does not re-coagulate uponheating in liquid state. The pH of the soymilk is suitably 5.5-7.4,preferably 6.5-7.4.

The following Examples further illustrate the present invention indetail but are not to be construed to limit the scope of thereof. In theExamples, “part” and “%” are by weight unless otherwise stated.

EXAMPLE 1

Ten parts of water were added to one part of soybeans from which seedcoats and hypocotyls had been removed, then the soybeans were soaked at30-50° C. for 60 minutes or longer. Three parts of hot water (90° C.)were added to one part of the soybeans with removed seed coats andhypocotyls which had absorbed with plenty of water (water content of40-55%), then the mixture was processed using a grinder (MasukouSangyou). A sodium bicarbonate solution was added to the mixture toadjust the pH to 7.4-8.0. The mixture was supplied into a homogenizer(APV) to homogenize at a pressure of 170 kg/cm². The ground andhomogenized mixture was centrifuged at 3000G for five minutes to obtaina soymilk and a tofu refuse. The soymilk was used as a raw soymilk. Theraw soymilk contained 9.0% of solid and 4.5% of protein, and had pH of7.5.

In order to examine the effects of the coagulants on the flavors, a saltpan bittern (Akou Kasei, magnesium chloride hexahydrate, purity of 92%),magnesium chloride (Kishida Kagaku, for food additive, purity of 95%) orcalcium sulfate dihydrate (Kishida Kagaku, for food additive, purity of98%) was added to the raw soymilk to assess the flavors. After the rawsoymilk was heated to 80° C., the coagulant dissolved or dispersed inwater was added thereto and mixed. The mixture was homogenized using ahomogenizer at a pressure of 100 kg/cm², sterilized with directhigh-temperature flash heating using steam (142° C. for four seconds),homogenized using a homogenizer at a pressure of 100 kg/cm², and thenassessed.

The addition of the coagulant masked the raw smell, the bitter taste andthe astringent taste of the soymilk from the flavor, and added goodbody. When the concentration of the added coagulant was 2.0% based onthe solid content of the raw soymilk (approximately 4% based on thecrude protein content of the soymilk), milk taste was recognized. Whenthe concentration of the added coagulant was 3.5% based on the solidcontent (approximately 7% based on the crude protein content of thesoymilk), the flavor was similar to a tofu and the astringent taste ofthe coagulant was slightly recognized. However, when the concentrationof the added coagulant was less than 1.0% based on the solid content ofthe raw soymilk (approximately 2% based on the crude protein content ofthe soymilk), the masking effect was little. When the concentration wasover 4.0% based on the solid content (approximately 8% based on thecrude protein content of the soymilk), the taste of the coagulant wasrecognized as a tang, and the effect of improvement the flavor was notobserved.

Furthermore, when the concentration of the added coagulant was 2.0%based on the solid content of the raw soymilk (approximately 4% based onthe crude protein content of the soymilk), both the viscosity and theparticle diameter were almost the same as those of a soymilk without acoagulant added even before the sterilization. However, when theconcentration of the added coagulant was 3.5% based on the solid contentof the soymilk (approximately 7% based on the crude protein content ofthe soymilk) or more, re-heating (70° C.) without sterilizing andhomogenizing the soymilk resulted in re-aggregation, even if it wasliquefied by homogenizing using a homogenizer at a pressure of 100kg/cm².

The viscosity and the particle diameter were reduced by adding acoagulant to a soymilk, heat-aggregating and sterilizing the soymilk.When the concentration of the coagulant added was changed from 2.0% to3.5% based on the solid content of the raw soymilk, no significantdifference in viscosity was observed after sterilization andhomogenization. Furthermore, neither aggregation nor water-separationwas observed for the both soymilks with added coagulant of 2.0% and 3.5%based on the solid content of the raw soymilk upon re-heating (85° C.for 5 minutes) although increase in viscosity was observed. Addition ofa bittern and magnesium chloride as coagulants resulted in a good finalflavor, whereas addition of calcium sulfate resulted in slightlyinferior body.

The results are summarized in Tables 1, 2 and 3.

Viscosity was measured using a B-type viscometer (BM type) at 10° C.Particle diameter was measured using a laser diffraction-type particlesize distribution-measuring instrument LA500 (Horiba Seisakusho).

TABLE 1 Physical properties and flavors of samples after homogenizationand before sterilization. Particle pH Viscosity diameter (15° C.) (cps)(μm) Flavor No 7.50 11 0.98 addition Bittern 0.8% 7.30 11 1.00 ΔIndistinguishable from no addition 2.0% 7.03 12 1.07 ⊚ Good body, milktaste feeling 3.5% 6.90 270 9.49 ∘ Tofu-like, thick MgCl₂ 0.8% 7.34 111.00 Δ Indistinguishable from no addition 2.0% 6.97 13 1.10 ⊚ Good body,milk taste feeling 3.5% 6.87 315 10.21 ∘ Tofu-like, thick CaSO₄ 0.8%7.30 11 1.00 Δ Indistinguishable from no addition 2.0% 6.88 14 2.13 ∘Good body, slight astringent taste 3.5% 6.77 1740 14.98 ∘ Tofu-like,slight astringent taste

TABLE 2 Physical properties and flavors of samples after sterilization.Particle pH Viscosity diameter (15° C.) (cps) (μm) Flavor No 7.50 110.91 addition Bittern 0.8% 7.30 11 0.92 Δ Indistinguishable from noaddition 2.0% 7.03 12 0.94 ⊚ Good body, milk taste feeling 3.5% 6.90 184.42 ∘ Tofu-like, thick MgCl₂ 0.8% 7.34 11 0.94 Δ Indistinguishable fromno addition 2.0% 6.97 12 0.96 ⊚ Good body, milk taste feeling 3.5% 6.8719 4.56 ∘ Tofu-like, thick CaSO₄ 0.8% 7.30 11 1.00 Δ Indistinguishablefrom no addition 2.0% 6.88 11 2.13 ∘ Good body, slight astringent taste3.5% 6.77 25 5.98 ∘ Tofu-like, slight astringent taste

TABLE 3 Physical properties and flavors of samples after sterilizationand homogenization. Particle pH Viscosity diameter (15° C.) (cps) (μm)Flavor No 7.50 10 0.84 addition Bittern 0.8% 7.30 10 0.82 ΔIndistinguishable from no addition 2.0% 7.03 10 0.81 ⊚ Good body, milktaste feeling 3.5% 6.90 12 3.21 ∘ Tofu-like, thick MgCl₂ 0.8% 7.34 110.82 Δ Indistinguishable from no addition 2.0% 6.97 11 0.85 ⊚ Good body,milk taste feeling 3.5% 6.87 12 3.51 ∘ Tofu-like, thick CaSO₄ 0.8% 7.3011 0.87 Δ Indistinguishable from no addition 2.0% 6.88 11 1.23 ∘ Goodbody, slight astringent taste 3.5% 6.77 16 3.54 ∘ Tofu-like, slightastringent taste

EXAMPLE 2

Effects of heating conditions of direct high-temperature flash heatingusing steam on viscosity, particle diameter and aggregation afterre-heating (85° C. for five minutes) were examined.

After a soymilk obtained as described in Example 1 was heated to 80° C.,magnesium chloride hexahydrate (Kishida Kagaku, for food additive,purity of 95%) dissolved in water was added thereto to a concentrationof 2.0% or 3.5% based on the solid content of the soymilk (approximately4% or approximately 7% based on the crude protein content of thesoymilk, respectively) and mixed. The mixture was homogenized using ahomogenizer at a pressure of 100 kg/cm². The homogenized mixture wassterilized with direct high-temperature flash heating using steam at142° C. for two or four seconds, homogenized using a homogenizer at apressure of 100 kg/cm², and then assessed. When the concentration of theadded coagulant was 2.0% based on the solid content of the soymilk,there was no difference between the result obtained for the treatmenttime of two seconds and that of four seconds. In this case, coagulationin tofu-like state was observed before sterilization. When theconcentration of the added coagulant was 3.5% based on the solid contentof the soymilk, two seconds of treatment did not result in decrease inviscosity or particle diameter after the subsequent homogenization tothe level observed for four seconds of treatment. The viscosity remainedhigh, and crumbling aggregates were observed in part upon re-heatingalthough coagulation was not observed. The viscosity and the particlediameter of the sample treated for two seconds and subjected to tworounds of homogenization decreased as compared with those subjected toone round of homogenization (data not shown in Table). However, theywere higher than those obtained for the sample treated for four seconds.In addition, improvement in aggregation after re-heating was notobserved. These results suggest that the sterilization time of directhigh-temperature flash heating using steam greatly affects the physicalproperties of the final product.

The results are shown in Table 4. In Table 4, viscosity was measuredusing a B-type viscometer (BM type) at 10° C. Particle diameter wasmeasured using a laser diffraction-type particle sizedistribution-measuring instrument LA500 (Horiba Seisakusho).

TABLE 4 Sterilization time and change in physical properties of samples.Added amount (%) 2.0 3.5 Treatment time (second) 2 4 2 4 Viscosity (cps)10.0 10.0 45.0 11.0 Particle diameter (μm) 0.84 0.81 5.53 3.10Re-aggregation No No Yes No

EXAMPLE 3

Effects of heating conditions of direct high-temperature flash heatingusing steam on viscosity, particle diameter and aggregation afterre-heating (85° C. for five minutes) were examined.

After a soymilk obtained as described in Example 1 was heated to 80° C.,magnesium chloride hexahydrate (Kishida Kagaku, for food additive, 95%)dissolved in water was added thereto to a concentration of 3.5% based onthe solid content of the soymilk and mixed. The mixture was homogenizedusing a homogenizer at a pressure of 100 kg/cm². The homogenized mixturewas sterilized with direct high-temperature flash heating using steam(120° C. for six seconds) or by indirect heating using plate heating(120° C. for six seconds), homogenized using a homogenizer at a pressureof 100 kg/cm², and then assessed. The viscosity and the particlediameter achieved by indirect heating using plate heating did notdecrease to the level of those achieved by direct high-temperature flashheating using steam even after the subsequent homogenization. Theviscosity remained high, and crumbling aggregates were observed in partupon re-heating although coagulation was not observed. In addition, itwas judged that the operation of the indirect heating using plateheating has problems, since the soymilk burned and stuck to the plate.These results suggest that the conditions of direct high-temperatureflash heating using steam, such as the pressure upon steam mixing duringsterilization, greatly affect the physical properties of the finalproduct.

The results are shown in Table 5. In Table 5, viscosity was measuredusing a B-type viscometer (BM type) at 10° C. Particle diameter wasmeasured using a laser diffraction-type particle sizedistribution-measuring instrument LA500 (Horiba Seisakusho).

TABLE 5 Mode of sterilization and heating and change in physicalproperties of samples. Mode of heating Direct with steam IndirectViscosity (cps) 13.0 55.0 Particle diameter (μm) 3.30 5.97Re-aggregation No Yes

EXAMPLE 4

Effects of pressure upon homogenization after sterilization onviscosity, particle diameter and aggregation after re-heating (85° C.for five minutes) were examined. After a soymilk obtained as describedin Example 1 was heated to 80° C., magnesium chloride (Kishida Kagaku,for food additive) dissolved in water was added thereto to aconcentration of 2.0% or 3.5% based on the solid content of the soymilk(approximately 4% or approximately 7% based on the crude protein contentof the soymilk, respectively) and mixed. The mixture was homogenizedusing a homogenizer at a pressure of 100 kg/cm². The homogenized mixturewas sterilized with direct high-temperature flash heating using steam(142° C. for four seconds), homogenized using a homogenizer at apressure of 50 kg/cm², 100 kg/cm² or 150 kg/cm², and then assessed.

All the conditions using the pressure of 50 kg/cm², 100 kg/cm² and 150kg/cm² resulted in decrease in viscosity and particle diameter and noaggregation after re-heating was observed.

The results are shown in Table 6. In Table 6, viscosity was measuredusing a B-type viscometer (BM type) at 10° C. Particle diameter wasmeasured using a laser 10 diffraction-type particle sizedistribution-measuring instrument LA500 (Horiba Seisakusho).

TABLE 6 Change in physical properties of samples due to conditions ofhomogenization after sterilization. Amount of magnesium chloride added:2.0% Pressure (kg/cm²) 0 50 100 150 Viscosity (cps) 13 9.5 10.0 9.0Particle diameter (μm) 0.94 0.82 0.81 0.76 Re-aggregation No No No NoAmount of magnesium chloride added: 3.5% Pressure (kg/cm²) 0 50 100 150Viscosity (cps) 18 12.0 11.0 10.5 Particle diameter (μm) 4.42 3.41 3.302.98 Re-aggregation No No No No

EXAMPLE 5

Ice creams were prepared using a soymilk obtained by the productionmethod of the present invention or a conventional soymilk obtained bysimilar procedure without adding a coagulant, and then the flavors wereassessed.

Ice creams used in a comparative test were prepared as follows.

70 parts of soymilk (solid content of 9%), 14 parts of granulated sugar,4 parts of powder starch syrup, 9 parts of vegetable oil and 3 parts ofwater were mixed. The mixture was heated to 80° C., homogenized using ahomogenizer, cooled, and then finished using an ice-cream freezer(SIMAC).

Thus-prepared ice creams were assessed by ten members in a comparativesensory test. Nine of the ten members assessed that the ice creamprepared using the soymilk obtained by the production method of thepresent invention as a raw material had less bean taste, bean smell, rawsmell, bitter taste and astringent taste and was more delicious thanthat obtained using the conventional soymilk.

EXAMPLE 6

Puddings were prepared using a soymilk obtained by the production methodof the present invention or a conventional soymilk obtained by similarprocedure without adding a coagulant, and then the flavors wereassessed.

Puddings used in a comparative test were prepared as follows.

55 parts of soymilk (solid content of 9%), 27 parts of whole egg and 18parts of fine white sugar were mixed, heated to 70° C., homogenizedusing a homogenizer, and heated in a steamer for 30 minutes forfinishing.

Thus-prepared puddings were assessed by ten members in a comparativesensory test. All of the ten members assessed that the pudding preparedusing the soymilk obtained by the production method of the presentinvention as a raw material had less bean taste, bean smell, raw smell,bitter taste and astringent taste, and was less glutinous and moredelicious than that obtained with the conventional soymilk.

EXAMPLE 7

Lactic acid bacterium-fermented soymilks were prepared using a soymilkobtained by the production method of the present invention or aconventional soymilk obtained by similar procedure without adding acoagulant, and then the flavors were assessed. Lactic acidbacterium-fermented soymilks used in a comparative test were prepared asfollows.

One part of culture broth of commercially available lactic acid bacteria(freeze-dried) as a starter was added to 99 parts of soymilk (solidcontent of 9%). Fermentation was conducted at 40° C. for seven hours.Then, the mixture was cooled to 7° C. to prepare a lactic acidbacterium-fermented soymilk. The pH of thus-obtained lactic acidbacterium-fermented soymilk was 4.3.

Thus-prepared lactic acid bacterium-fermented soymilks were assessed byten members in a comparative sensory test. All of the ten membersassessed that the lactic acid bacterium-fermented soymilk prepared usingthe soymilk obtained by the production method of the present inventionas a raw material had less raw smell, bitter taste and astringent taste,was smoother, left a pleasant aftertaste, and was more delicious thanthat obtained with the conventional soymilk as a raw material.

As described above, a soymilk with a stable quality and an improvedflavor in a simple manner and without impairing the flavor of thesoymilk as compared with conventional methods in which a coagulant isadded to a soymilk can be obtained according to the present invention.In other words, the soymilk of the present invention has good body, isin liquid state with low viscosity, and does not re-coagulate uponheating.

Therefore, the soymilk of the present invention can be utilized as akneading material for confectionery or bakery and a filling materialsuch as cream, as well as materials for fermentation foods, drinks, icecreams, desserts, aquatic or live-stock paste products, cooked dailydish and the like, which have an excellent flavor.

What is claimed is:
 1. A method of producing a soymilk in liquid form,comprising adding a coagulant to a starting soymilk, homogenizing,treating with direct high-temperature flash heating using steam, andthen homogenizing the mixture.
 2. The method according to claim 1,wherein the pH of the starting soymilk is adjusted to 7-8.
 3. The methodaccording to claim 1, wherein the coagulant is one or more selected fromthe group consisting of a bittern, a magnesium salt, a calcium salt andglucono-δ-lactone.
 4. The method according to claim 1, wherein th eamount of the added coagulant is 2-8% based on the crude protein contentof the soymilk.
 5. The method according to any one of claim 1, whereinthe direct high-temperature flash heating is conducted at 120-150° C.for 2-10 seconds.
 6. The method according to any one of claim 1, whereinthe homogenization is conducted using a homogenizer at a pressure of5-200 kg/cm².
 7. The method according to any one of claim 1, wherein thepH of the produced soymilk is 5.5-7.4.
 8. The method according to claim2, wherein the coagulant is one or more selected from the groupconsisting of a bittern, a magnesium salt, a calcium salt andglucono-δ-lactone.
 9. The method according to claim 2, wherein theamount of the added coagulant is 2-8% based on the crude protein contentof the soymilk.
 10. The method according to claim 3, wherein the amountof the added coagulant is 2-8% based on the crude protein content of thesoymilk.
 11. The method according to claim 2, wherein the directhigh-temperature flash heating is conducted at 120-150° C. for 2-10seconds.
 12. The method according to claim 3, wherein the directhigh-temperature flash heating is conducted at 120-150° C. for 2-10seconds.
 13. The method according to claim 4, wherein the directhigh-temperature flash heating is conducted at 120-150° C. for 2-10seconds.
 14. The method according to claim 2, wherein the homogenizationis conducted using a homogenizer at a pressure of 5-200 kg/cm².
 15. Themethod according to claim 3, wherein the homogenization is conductedusing a homogenizer at a pressure of 5-200 kg/cm².
 16. The methodaccording to claim 4, wherein the homogenization is conducted using ahomogenizer at a pressure of 5-200 kg/cm².
 17. The method according toclaim 5, wherein the homogenization is conducted using a homogenizer ata pressure of 5-200 kg/cm².
 18. The method according to claim 2, whereinthe pH of the produced soymilk is 5.5-7.4.
 19. The method according toclaim 3, wherein the pH of the produced soymilk is 5.5-7.4.
 20. Themethod according to claim 4, wherein the pH of the produced soymilk is5.5-7.4.
 21. The method according to claim 5, wherein the pH of theproduced soymilk is 5.5-7.4.
 22. The method according to claim 6,wherein the pH of the produced soymilk is 5.5-7.4.
 23. The methodaccording to claim 4, wherein the coagulant is a magnesium salt or acalcium salt, and is added in an amount of 0.24-1.9% as magnesium orcalcium based on the crude protein content of the soymilk.
 24. Themethod according to claim 9, wherein the coagulant is a magnesium saltor a calcium salt, and is added in an amount of 0.24-1.9% as magnesiumor calcium based on the crude protein content of the soymilk.
 25. Themethod according to claim 10, wherein the coagulant is a magnesium saltor a calcium salt, and is added in an amount of 0.24-1.9% as magnesiumor calcium based on the crude protein content of the soymilk.